An air-conditioning unit of the type in question is known from EP 2 236 327 A1, for example. It comprises a multipart housing, which has an air-conditioning segment and a blower segment. A blower for driving the air flow is arranged in the blower segment. For this purpose, the blower has an impeller and an electric motor for driving the impeller. During the operation of the blower, the impeller rotates about an axis of rotation. The blower can expediently be configured as a radial blower, and therefore the associated impeller is then configured as a radial impeller. The components of the air-conditioning unit which are required to air-condition the air flow, e.g. at least one air filter, an evaporator of a refrigeration circuit and at least one heating device, are then accommodated in the air-conditioning segment of the housing. The heating device can be configured as an electric heating device, e.g. as a PTC element, where PTC stands for positive temperature coefficient. A heating device of this kind can furthermore be configured as a heat exchanger, through which, on the one hand, the air flow to be air-conditioned and, on the other hand, a heat transfer medium of a heating circuit can flow.
Water can arise in air-conditioning units of this kind and must be discharged from the housing in order to avoid odours. It is primarily condensation at the evaporator of water carried along in vapour form in the flow which can occur here. In this case, the condensate can be discharged from the housing in a suitable manner. Moreover, there is also the possibility, especially in the case of vehicle applications, that the fresh air drawn in by the blower will already be carrying liquid water in droplet form. In this case, this water can be deposited in the housing on the suction side of the blower and on the pressure side of the blower.
The abovementioned EP 2 236 327 A1 discloses that water which is deposited in the housing can be discharged by means of a suction-side drainage path and by means of a pressure-side drainage path, wherein the two drainage paths are routed within the housing to a condensed water drain, through which condensed water and deposited water can be discharged from the housing.
Other air-conditioning units, the housing of which is equipped with at least one drainage path, are known from DE 10 2009 009 065 A1 and from EP 2 00 0 338 A1.
To improve the performance of the blower and/or to reduce the noise generated by the blower, EP 2 388 159 A2 and EP 2 292 935 A2, for example, disclose the formation on the housing of a blower tongue, which forms a wall segment for radially delimiting a pressure chamber in which the pressure side of the blower is situated. Here, the blower tongue is arranged at a transition from said pressure chamber to a duct leading away therefrom. It has been found that the geometry of this blower tongue has a decisive effect on the efficiency of the blower and on the noise generated by the blower.